Romulox is a blue tar monster. His skin looks extremely bumpy, which may indicate that he is composed of tar. He has two strange horns protruding from his head, and he almost always speaks in a very condescending, bored tone. In his first appearance, he was wearing women's underwear for reasons that were never explained. In "The Last One," his second appearance, Romulox wore a costume that mimicked Oog's outfit.
Despite being a hideous tar monster, Romulox is a snob (possibly even a hipster) who constantly obtains expensive objects, some of which serve no purpose other than to make people believe he is better than them. During his first appearance on the show, he continuously talked down to everyone, except whomever he was on the phone with.
Despite all of his pretentiousness, Romulox appears to have very little real world knowledge. At one point, he rudely interrupts Mothmonsterman's story about buying an inexpensive house in the country of Belize to dismissively state how "Belize is a very expensive city, actually..." He also mistook Shake's hands for generic version of his "original yellows [gloves]." It may be possible that this incident was planned, as he later stole Oog's fashion sense in "The Last One."
In "PDA," Shake claims that Romulox has stolen his PDA. The Aqua Teens go to the Trenton Tar Pits to find him, but Frylock decides he has had enough of Shake's antics. The Aqua Teens return home to find Romulox using a hands-free cell phone in their house. Romulox continuously points out things he has the Aqua Teens do not have, including the "easy-flow elbow" (which seems to serve no purpose other than to make people jealous). Romulox decides to give his PDA to Shake (who was making the whole thing up), and then leaves using a grappling hook.
Romulox's second appearance was in "The Last One," where he finished off the last few parts of The Broodwich (the sun-dried tomatoes), which sent him to the Broodwich Dimension. He made his last appearance in "The Greatest Story Ever Told."
- In many ways, Romulox is similar in personality to Master Shake. Both characters have been known to spend a large amount of money on things solely to impress people and believe they are better than everyone.
- He makes a brief cameo in the opening sequence for Aqua Something You Know Whatever.